98 Papers from the Department of Marine Biology. 
A solution of phosphotungstic acid added to crude luciferase solu- 
tion gives a voluminous precipitate which, if washed quickly in running 
water on the filter and then suspended in water, does not completely 
dissolve, but gives a good light if luciferin is added. It dissolves if a 
trace of dilute NH,OH solution is added. The filtrate gives no light 
with excess luciferin, even though it contains some material which will 
precipitate on addition of more phosphotungstic acid. 
Tannic acid added in slight excess to luciferase gives an abundant 
precipitate which contains luciferase and will give a good light with 
luciferin if suspended in water. It does not completely dissolve, even 
on addition of dilute NH,OH solution. The filtrate gives a very faint 
light on addition of an excess of luciferin, even though an excess of 
tannic acid was used to precipitate and all precipitable material was 
thrown down. 
Saturated aqueous picric acid added in equal volume to crude lucif- 
erase solution gives a not very abundant precipitate which, if filtered 
off, washed quickly with water, and suspended in water, does not com- 
pletely dissolve. If luciferin is added the precipitate does dissolve and 
a good light appears. Dilute NH,OH solution causes the precipitate to 
dissolve. The filtrate gives a very faint light when an excess of lucif- 
erin is added, even though everything was precipitated that would pre- 
cipitate with picric acid and an excess of the latter was present. The 
excess of picric acid was not sufficient to harm the luciferin used in testing. 
Attempts were made to study the adsorption of luciferase by picric 
acid, tannic acid, and phosphotungstic acid previpitates of egg albumen. 
The difficulty is that these precipitates tend to go in solution again 
and it is very difficult to remove by washing (centrifuging and decan- 
tation) the precipitant. This is especially well observed in the case 
of the picric acid-egg albumen precipitate, where the supernatant 
liquid has a yellow color after prolonged washing. However, the 
results show that very little adsorption takes place, not nearly enough 
to explain the complete or nearly complete precipitation of luciferase 
from crude solution by these reagents. 
Luciferase is, therefore, completely precipitated by phosphotungstic 
acid and very nearly completely precipitated by tannic and picric acids 
without harm. 
Phosphotungstic acid added to a solution of crude luciferin to slight 
excess gives a bulky precipitate which can be filtered off and the filtrate 
is perfectly clear. It gives no further precipitate with phosphotungstic 
acid, but contains a small amount of luciferin, as a faint light appears 
when luciferase in excess (since luciferase is also precipitated by the 
excess phosphotungstic acid present) is added. The precipitate 
washed on the filter with dilute phosphotungstic acid does not dissolve 
completely in water, but partly dissolves, forming an opalescent solution. 
It is brought into solution by adding crude luciferase or a trace of dilute 
